[Xen-devel] [PATCH 2/5] xen/arm: optee: check for preemption while freeing shared buffers

[Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>]

Now we have limit for one shared buffer size, so we can be sure that
one call to free_optee_shm_buf() will not free all
MAX_TOTAL_SMH_BUF_PG pages at once. Thus, we now can check for
hypercall_preempt_check() in the loop inside
optee_relinquish_resources() and this will ensure that we are not
missing preemption.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
---
 xen/arch/arm/tee/optee.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index f4fa8a7758..a84ffa3089 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -634,14 +634,14 @@ static int optee_relinquish_resources(struct domain *d)
     if ( hypercall_preempt_check() )
         return -ERESTART;
 
-    /*
-     * TODO: Guest can pin up to MAX_TOTAL_SMH_BUF_PG pages and all of
-     * them will be put in this loop. It is worth considering to
-     * check for preemption inside the loop.
-     */
     list_for_each_entry_safe( optee_shm_buf, optee_shm_buf_tmp,
                               &ctx->optee_shm_buf_list, list )
+    {
+        if ( hypercall_preempt_check() )
+            return -ERESTART;
+
         free_optee_shm_buf(ctx, optee_shm_buf->cookie);
+    }
 
     if ( hypercall_preempt_check() )
         return -ERESTART;
-- 
2.22.0

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